Well it seems that after installing that extension your layout was changed. I see in your head section that the template is using the modern theme instead of the hellojynxx theme. Check to make sure in System–>Configuration–>Design that the package and themes are set up according to your template. If they are set right, perhaps folders or files may have been overwritten on install and Magento can’t find them in the hellojynxx template folder, so it’s taking those missing files from the modern template.
If you change the settings and the problem persists (after clearing your cache) then post those settings here. You may have to give HT an ftp access to help you with this one since it involves another extension (which should work with the theme).
Hi, we can’t assure that all the extensions will work with the themes. It’s like any other product, you buy the product and it has to work 100% correctly by it self, but if you add something to the product that we don’t produce….,we can’t assure it will work correctly. With every theme we develop, we try to make it as compatible as possible with the standar extensions.
I recommend you to make the tabs manually, you can check our tutorial here: